Catalytic dehydrogenative aromatization(CDA)has emerged as a powerful strategy for the synthesis of substituted phenols.However,most of the known CDA methods suffer from limited functional group compatibility due to t...Catalytic dehydrogenative aromatization(CDA)has emerged as a powerful strategy for the synthesis of substituted phenols.However,most of the known CDA methods suffer from limited functional group compatibility due to the use of strong oxidants,reductants,or bases.Herein,we report a(cis-P_(2)Cl)Ir-catalyzed CDA reaction enabled by transfer dehydrogenation(TD).This catalytic system is effective for CDA of both cyclohexanone and cyclohexanol derivatives and demonstrates excellent tolerance toward a variety of functional groups,including readily oxidizable electron-rich heterocycles.DFT studies further reveal that the(cis-P_(2)Cl)Ir catalyst is thermodynamically disfavored for the formation of a potential out-of-cycle catalyst species,iridium phenoxyl hydride complex,via oxidative addition of the phenol O–H bond,thereby preventing catalyst inhibition observed in the previously reported TD system.展开更多
Phenols are ubiquitous substructures in natural products and bioactive compounds.However,practical methods for the direct construction of phenols under mild conditions remain challenging.Herein,a photocatalytic accept...Phenols are ubiquitous substructures in natural products and bioactive compounds.However,practical methods for the direct construction of phenols under mild conditions remain challenging.Herein,a photocatalytic acceptorless hydrogen-evolution aromatization of cyclohexanones or cyclohexenones at room temperature has been developed.The reaction features the visible-light and cobalt co-catalyzed sequential dehydrogenation of in-situ formed enol silyl ethers,which are regarded as a challenging process.This operationally simple method enables the synthesis of a series of phenols with diverse substitution patterns from cyclohexanones or cyclohexenones.Moreover,diverse substituted 1,2-,1,3-,and 1,4-benzenediols were obtained from cyclohexanediones,providing a general and straightforward method for the synthesis of phenols from simple starting materials under mild conditions.展开更多
Cyclohexanone oxime serves as a crucial intermediate in the synthesis of caprolactam,which is an essential precursor for manufacturing nylonfibers,high-performance engineering plastics,and specialized plasticfilms.Cat...Cyclohexanone oxime serves as a crucial intermediate in the synthesis of caprolactam,which is an essential precursor for manufacturing nylonfibers,high-performance engineering plastics,and specialized plasticfilms.Catalytic hydrogenation of nitrocyclohexane to cyclohexanone oxime has been documented to be an atom-economical,green and environmentally friendly process.In this review,wefirst introduce the current design rules of catalysts for catalytic hydrogenation of nitrocyclohexane in terms of both active metals and supports.Secondly,we discuss the influence of solvent effects on the cyclohexanone oxime from the nitrocyclohexane conversion.In addition,we concisely discuss typically proposed reaction pathways for the hydrogenation of nitrocyclohexane to produce cyclohexanone oxime.Finally,we provide our perspectives on some issues for catalytic conversion of nitrocyclohexane to cyclohexanone oxime in the future.展开更多
Constructing electrocatalytic overall reaction technology to couple the electrosynthesis of adipic acid with energy-saving hydrogen production is of significant for sustainable energy systems.However,the development o...Constructing electrocatalytic overall reaction technology to couple the electrosynthesis of adipic acid with energy-saving hydrogen production is of significant for sustainable energy systems.However,the development of highly-active bifunctional electrocatalysts remains a challenge.Herein,3D hierarchical nickel-copper alloying arrays with dendritic morphology are manufactured by a simple electrodeposition process,standing for the excellent bifunctional electrocatalyst towards the co-production of adipic acid and H_(2)from cyclohexanone and water.The membrane-free flow electrolyzer of Cu_(0.81)Ni_(0.19)/NF shows the superior electrooxidation performance of ketone-alcohol(KA)oil with high faradaic efficiencies of over 90%for adipic acid and H_(2),robust stability over 200 h as well as a high yield of 0.6 mmol h^(-1) for adipic acid at 100 mA cm^(-2).In-situ spectroscopy indicates the Cu_(0.81)Ni_(0.19)alloy contributes to forming more active NiOOH species to involve in the conversion of cyclohexanone to adipic acid,while the proposed reaction pathway undergoes the 2-hydroxycyclohexanone and 2,7-oxepanedione intermediates.Moreover,the theoretical calculations confirm that the optimal electronic interaction,boosted reaction kinetics as well as improved adsorption free energy of reaction intermediates,synergistically endows Cu_(0.81)Ni_(0.19)alloy with superior bifunctional performance.展开更多
The liquid phase Beckmann rearrangement of cyclohexanone oxime (CHO) using fuming sulfuric acid as a catalyst is a traditional method for preparing ε-caprolactam (CPL). This process has drawbacks, such as environment...The liquid phase Beckmann rearrangement of cyclohexanone oxime (CHO) using fuming sulfuric acid as a catalyst is a traditional method for preparing ε-caprolactam (CPL). This process has drawbacks, such as environmental pollution, corrosion of equipment, and low added value of by-product ammonium sulfate. This article designed and prepared a green silica gel-supported trifluoromethanesulfonic acid catalyst for the liquid-phase Beckmann rearrangement of CHO to prepare (CPL). The influencing factors of catalyst preparation and the optimal reaction conditions for Beckmann rearrangement were investigated. It was found that the optimal conditions for catalyst preparation were as follows: raw material silica gel:trifluoromethanesulfonic acid = 1:0.2 (mass ratio), room temperature, stirring time of 2.5 hours, and solvent of acetonitrile, silica gel mesh size is 100 - 200. The optimal reaction conditions for Beckmann rearrangement are CHO: catalyst = 1:2 (mass ratio), temperature of 130˚C, solvent of benzonitrile, volume of 30 mL/g CHO, and reaction time of 4 hours. Under the above conditions, the conversion of CHO is 90%, and the selectivity of CPL is 90%.展开更多
Small-crystal TS-1 was synthesized via a seed-induced approach using ammonia as the alkali source and tetrapropylammonium bromide as an auxiliary structure-directing agent. The TS-1 samples were characterized using X-...Small-crystal TS-1 was synthesized via a seed-induced approach using ammonia as the alkali source and tetrapropylammonium bromide as an auxiliary structure-directing agent. The TS-1 samples were characterized using X-ray diffraction, N2 adsorption-desorption, Fourier-transform infrared spectroscopy, inductively coupled plasma atomic emission spectroscopy, scanning electron microscopy, and ultraviolet-visible spectroscopy. The use of the colloidal seed reduced the crystal size, and an appropriate amount of silicalite-1 seed assisted Ti incorporation into the TS-1 framework. This method reduces the cost of TS- 1 synthesis because a significantly smaller amount of tetrapropylammonium hydroxide is used. The catalytic performance of the synthesized small-crystal TS-1 samples in cyclohexanone ammoximation was better than that of bulk TS-1 as a result of improved diffusion and a larger number of active tetrahedral Ti centers.展开更多
A natural polymer catalyst, silica-supported chitosan palladium complex (abbr. as SiO2-CS-Pd) was found to catalyze the hydrogenation of phenol and cresols to corresponding cyclohexanones in high yield and 100% select...A natural polymer catalyst, silica-supported chitosan palladium complex (abbr. as SiO2-CS-Pd) was found to catalyze the hydrogenation of phenol and cresols to corresponding cyclohexanones in high yield and 100% selectivity at 70 degrees C and 1.01325 x 10(5) Pa mild conditions. N/Pd molar ratio in the complex, temperature and solvents have much influence on the reaction. The reactivity order of reactants was found to be: phenol >m->p->o- The catalyst is stable during the reaction and could be repeatedly used for several times without much decrease in its catalytic activity.展开更多
A series of Pd catalysts were prepared on different supports（Fe2O3,SiO2,ZnO,MgO,Al2O3,carbon,and Amberlyst-45） and used in the selective hydrogenation of phenol to cyclohexanone in water.The Amberlyst-45 supported P...A series of Pd catalysts were prepared on different supports（Fe2O3,SiO2,ZnO,MgO,Al2O3,carbon,and Amberlyst-45） and used in the selective hydrogenation of phenol to cyclohexanone in water.The Amberlyst-45 supported Pd catalyst（Pd/A-45） was highly active and selective under mild conditions（40-100 ℃,0.2-1 MPa）,giving a selectivity of cyclohexanone higher than 89%even at complete conversion of phenol.Experiments with different Pd loadings（or different particle sizes） confirmed that the formation of cyclohexanone was a structure sensitive reaction,and Pd particles of12-14 nm on Amberlyst-45 gave better selectivity and stability.展开更多
A series of indazol-2-yl（pyridin-4-yl）methanones, 4 were acquired from 2,6-bisbenzylidene cyclohex- anones, 3 and anti-tubercular drug （isoniazid）, and their anti-tubercular impacts were screened. Among the test c...A series of indazol-2-yl（pyridin-4-yl）methanones, 4 were acquired from 2,6-bisbenzylidene cyclohex- anones, 3 and anti-tubercular drug （isoniazid）, and their anti-tubercular impacts were screened. Among the test compounds used against Mycobacterium tuberculosis H37 Ra cell line in the microplate alamar blue assay, the compounds 4g-j revealed moderate anti-tubercular activity with MIC 12.5 μg/mL, comparable to standard drugs （streptomycin, MIC, 6.25 μg/mL, pyrazinamide, isoniazid and ciprofloxacin with MICs of 3.125 μg/mL）.展开更多
A new environmental friendly catalyst,H_(4)SiW_(12)O_(40)/PAn was prepared andidentified by means of FT-IR,XRD and TG/DTA.Cyclohexanone 1,2-propanediol ketal was synthesizedfrom cyclohexanone and 1,2-propanediol in th...A new environmental friendly catalyst,H_(4)SiW_(12)O_(40)/PAn was prepared andidentified by means of FT-IR,XRD and TG/DTA.Cyclohexanone 1,2-propanediol ketal was synthesizedfrom cyclohexanone and 1,2-propanediol in the presence of H_(4)SiW_(12)O_(40)/PAn The factorsinfluencing tlie synthesis were discussed and the best conditions were found out.The optimumconditions are:molar ratio of cyclohexanone to 1,2-propanediol is 1:1.4,the quantity of catalystis equal to 1.0 percent of feed stocks,and the reaction time is 40 min.H_(4)SiW_(12)O_(40)/PAn is anexcellent catalyst for synthesizing cyclohexanone 1,2-propanediol ketal and its yield can reachover 96.5 percent.展开更多
An innovative green process of producing ε-caprolactam was proposed by integrating ammoximation and Beckmann rearrangement effectively. As a first part of the new process, TS-1 molecular sieve-catalyzed synthesis of ...An innovative green process of producing ε-caprolactam was proposed by integrating ammoximation and Beckmann rearrangement effectively. As a first part of the new process, TS-1 molecular sieve-catalyzed synthesis of cyclohexanone oxime from cyclohexanone, ammonia and hydrogen peroxide was carried out in a batch plant. Cyclohexane was used as the solvent in the three-phase reaction system. The influences of essential process parameters on ammoximation were investigated. Under the reaction conditions as catalyst content of 2.5% (by mass); H 2 O 2 /yclohexanone molar ratio of 1.10; NH 3 /cyclohexanone molar ratio of 2.20; reaction temperature of 343 K; reaction time of 5 h, high conversion of cyclohexanone and selectivity to oxime (both>99%) were obtained. Thus, the three-phase ammoximation process showed equal catalytic activity as TS-1 but much more convenient and simpler for the separation of catalyst in comparison to the industrial two-phase system with t-butanol used as solvent.展开更多
The selective hydrogenation of phenol to cyclohexanone is an important process in the chemical industry.However,achieving high selectivity at high conversion rates is highly challenging,particularly under continuous r...The selective hydrogenation of phenol to cyclohexanone is an important process in the chemical industry.However,achieving high selectivity at high conversion rates is highly challenging,particularly under continuous reaction conditions.Here,we found that the presence of Na alkaline additives(NaX,X=CO3^2–,HCO^3–,or OH^–)on Pd/Al2O3 not only promoted the phenol conversion from 8.3%to>99%but also increased the cyclohexanone selectivity from 89%to>97%during the continuous hydrogenation of phenol on a fixed bed reactor.After 1200 h of continuous reaction,no activity or selectivity attenuation was observed and the turnover number was approximately 2.9×10^5.Density functional theory calculations,spectroscopic,and dynamics studies demonstrated that the addition of NaX greatly promoted phenol adsorption and hydrogen activation,thereby improving catalytic activity.Simultaneously,the formation of a“-C=O-Na-”intermediate inhibited the excessive hydrogenation and intermolecular coupling of cyclohexanone,leading to high selectivity.展开更多
In the absence of catalyst,70%hydrogen peroxide was used to oxidize succinic anhydride to solid monoperoxysuccinic acid(PSA).Then PSA was applied to synthesis ofε-caprolactone(ε-CL)by oxidation of cyclohexanone in t...In the absence of catalyst,70%hydrogen peroxide was used to oxidize succinic anhydride to solid monoperoxysuccinic acid(PSA).Then PSA was applied to synthesis ofε-caprolactone(ε-CL)by oxidation of cyclohexanone in the heterogeneous system.In order to achieve material recycle,solid precipitated in the process of synthesizingε-CL was dehydrated via reactive distillation followed by recrystallization to prepare succinic anhydride,which was characterized by IR(infrared spectra)and1HNMR(1H nuclear magnetic resonance).Effects of molar ratio of PSA to cyclohexanone,acetic acid dosage,reaction temperature,reaction time on conversion of cyclohexanone,yield and selectivity ofε-CL were investigated respectively.The results indicated that conversion of cyclohexanone,yield and selectivity ofε-CL were upto 98.1%,97.5%and 99.4%respectively under the optimal conditions.In addition,in the process of synthesizing succinic anhydride,the optimal yield of succinic anhydride reached 67.4%.展开更多
An intrinsic kinetics of cyclohexanone ammoximation in the liquid phase over titanium silicate molecular sieves is investigated in an isothermal slurry reactor at different initial reactant concentrations, catalyst lo...An intrinsic kinetics of cyclohexanone ammoximation in the liquid phase over titanium silicate molecular sieves is investigated in an isothermal slurry reactor at different initial reactant concentrations, catalyst loading, and reaction temperature. The rate equations are developed by analyzing data of kinetic measurements. More than 10 side reactions were found. H2O2 decomposition reaction must be considered and other side reactions can be neglected in the kinetic modeling. The predicted values of reaction rates based on the kinetic models are almost consistent with experimental ones. The models have guidance to the selection of reactor types and they are useful to the design and operation of reactor used.展开更多
Hollow titanium silicalite （HTS） molecular sieve has been synthesized, and information on its structure, physico- chemical characterization, as well as surface property was investigated by a host of analytical metho...Hollow titanium silicalite （HTS） molecular sieve has been synthesized, and information on its structure, physico- chemical characterization, as well as surface property was investigated by a host of analytical methods, such as XRF, XRD, low-temperature N2 adsorption/desorption, TEM, FT-IR, UV-Vis, 29Si MAS NIVIR, and XPS techniques. The characterization results suggest that HTS zeolite has a special hollow crystal structure and its mesopore volume is larger than that of TS-1 zeolite. The titanium species in this zeolite are composed of the framework tetrahedral Ti （IV） ions and extra-framework octahedral Ti （IV） ions, which tend to disperse into its bulk phase. This zeolite material also has been applied to catalyze the cyclohexanone oxidation process, and the products are not completely consistent with those results obtained by using TS-1 zeolite, which might be caused by their difference in pore structure and pore volume, especially the mesopore volume. Cy- clohexanone oxidation catalyzed by HTS zeolite is a representative consecutive reaction, the main target products of which are e-caprolactone, 6-hydroxyhexanoic acid and adipic acid. The effect of H202/cyclohexanone mole ratio on the cyclohexa- none conversion, the total target product selectivity, the distribution of three target products selectivity and their variations along with reaction time is also researched and analyzed, which indicate that HTS zeolite shows a high performance for the Baeyer-Villiger reaction of cyclohexanone and catalytic oxidation of 6-hydroxyhexanoic acid under mild conditions, and the quantity of active surface titanium species as well as the pore structure and mesopore volume controlling the mass diffusion rate are the key factors determining the catalytic activity of HTS zeolite and product selectivity.展开更多
Selective phenol hydrogenation is a green approach to produce cyclohexanone.It still remains a big challenge to prepare efficient supports of the catalysts for the phenol hydrogenation via a simple and cost-effective ...Selective phenol hydrogenation is a green approach to produce cyclohexanone.It still remains a big challenge to prepare efficient supports of the catalysts for the phenol hydrogenation via a simple and cost-effective approach.Herein,a facile approach was developed,i.e.,direct calcination of activated carbon(AC)under argon at high temperature,to improve its structure and surface properties.The modified AC materials were supported with Pd nanoparticles(NPs)to fabricate the Pd/C catalysts.The as-prepared Pd/C600 catalyst exhibits superior catalytic performance in the phenol hydrogenation,and its turnover frequency(TOF)value is 199.2 h^-1,1.31 times to that of Pd/C-raw.The Pd/C600 catalyst presents both better hydrophobicity and more structural defects,contributing to the improved dispersibility in the reaction solution(phenol-cyclohexane),the better Pd dispersion and the smaller Pd size,which result in the enhancement of the catalytic performance.Furthermore,the as-prepared Pd/C600 catalyst shows a good recyclability.展开更多
Mesoporous titanium silicalite-1(TS-1)was hydrothermally synthesized with the addition of triethanolamine(TEA)in the conventional process, and used in the cyclohexanone ammoximation in a continuous slurry reactor. The...Mesoporous titanium silicalite-1(TS-1)was hydrothermally synthesized with the addition of triethanolamine(TEA)in the conventional process, and used in the cyclohexanone ammoximation in a continuous slurry reactor. The as-prepared TS-1 was characterized with X-ray diffraction(XRD), scanning electron microcopy(SEM), N_2 adsorption-desorption, Fourier transform infrared(FT-IR)spectroscopy, UV-Visible(UV-Vis)diffuse reflectance spectra and UV Raman spectroscopy. The results indicated that the addition of TEA resulted in the formation of mesopores and the slight increase of framework titanium in TS-1. TS-1 synthesized with the addition of TEA exhibited a higher stability in the cyclohexanone ammoximation than that without the addition of TEA, attributing to the increase of mesopore volumes and the slight increase of the framework titanium in TS-1. However, when the addition of TEA was up to TEA/SiO_2 ratio of 0.24, the crystallinity and framework titanium of TS-1 decreased markedly, and the average crystal sizes of TS-1 increased, with the catalyst stability becoming poor.展开更多
Two clean liquid–phase cyclohexanone oxidation routes catalyzed by DHBEA and HTS zeolites, in the absence of organic solvents, have been developed for producing high value-added chemical intermediates. Under optimize...Two clean liquid–phase cyclohexanone oxidation routes catalyzed by DHBEA and HTS zeolites, in the absence of organic solvents, have been developed for producing high value-added chemical intermediates. Under optimized conditions,the cyclohexanone conversion reaches up to 60%, and the selectivity of total target products(ε-caprolactone, 6-hydroxyhexanoic acid and adipic acid) is over 90% achieved by the HTS zeolite; while both cyclohexanone conversion and the 6-hydroxyhexanoic acid selectivity are over 95% obtained on the DHBEA zeolite. Both the Lewis and Br鰊sted acid sites of DHBEA zeolite can preferentially activate the carbonyl group of cyclohexanone without any impact on H_2O_2 molecules.Meanwhile, the HTS zeolite can predominantly make H_2O_2 more reactive, which agrees well with the molecular calculation results. Hence, two different Baeyer-Villiger oxidation mechanisms based on the activation of H_2O_2 and cyclohexanone are proposed. Then, 6-hydroxyhexanoic acid is formed via the ring-opening of ε-caprolactone. However, C-OH groups cannot be reactivated by DHBEA zeolite, leading to insignificant adipic acid formation, while the selectivity of adipic acid is 28.5% obtained on the HTS zeolite. Consequently, the higher catalytic performance of the DHBEA zeolite is ascribed to its larger amount of active sites and greater diffusion features than those of HTS zeolite.展开更多
A new kind of inorganic polymer, viz, silica-supported polytitazane (Ti-N), and its platinum complex (Ti-N-Pt) were prepared. Cyclohexanone can be obtained in a maximum yield of about 62.2% in the hydrogenation of phe...A new kind of inorganic polymer, viz, silica-supported polytitazane (Ti-N), and its platinum complex (Ti-N-Pt) were prepared. Cyclohexanone can be obtained in a maximum yield of about 62.2% in the hydrogenation of phenol over Ti-N-Pt at room temperature under atmospheric pressure. The effects of mole ratio of N/Pt in the complex, concentration of the catalyst and reaction temperature on the catalytic activity and selectivity have been studied. The complex can be reused several times without loss in its catalytic activity.展开更多
基金support from the National Key R&D Program of China(2021YFA1501700)National Natural Science Foundation of China(22425012,22293013)+3 种基金the Shanghai Sailing Program(24YF2756700)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0610000,XDB1180000)CAS Project for Young Scientists in Basic Research(YSBR-O94)Science and Technology Commission of Shanghai Municipality(23JC1404400).
文摘Catalytic dehydrogenative aromatization(CDA)has emerged as a powerful strategy for the synthesis of substituted phenols.However,most of the known CDA methods suffer from limited functional group compatibility due to the use of strong oxidants,reductants,or bases.Herein,we report a(cis-P_(2)Cl)Ir-catalyzed CDA reaction enabled by transfer dehydrogenation(TD).This catalytic system is effective for CDA of both cyclohexanone and cyclohexanol derivatives and demonstrates excellent tolerance toward a variety of functional groups,including readily oxidizable electron-rich heterocycles.DFT studies further reveal that the(cis-P_(2)Cl)Ir catalyst is thermodynamically disfavored for the formation of a potential out-of-cycle catalyst species,iridium phenoxyl hydride complex,via oxidative addition of the phenol O–H bond,thereby preventing catalyst inhibition observed in the previously reported TD system.
基金Financial support from NSFC(21971101 and 22171127)Guangdong Basic and Applied Basic Research Foundation(2022A1515011806)+4 种基金Department of Education of Guangdong Province(2021KTSCX106)Guangdong Province Graduate Education Innovation Program(2022JGXM054)The Pearl River Talent Recruitment Program(2019QN01Y261)Shenzhen Science and Technology Innovation Committee(JCYJ20220519201425001)GuangdonggProvincialKeyLaboratoryofCatalysis(2020B121201002)is sincerely acknowledged.We acknowledge the assistance of SUsTech Core Research Facilities.
文摘Phenols are ubiquitous substructures in natural products and bioactive compounds.However,practical methods for the direct construction of phenols under mild conditions remain challenging.Herein,a photocatalytic acceptorless hydrogen-evolution aromatization of cyclohexanones or cyclohexenones at room temperature has been developed.The reaction features the visible-light and cobalt co-catalyzed sequential dehydrogenation of in-situ formed enol silyl ethers,which are regarded as a challenging process.This operationally simple method enables the synthesis of a series of phenols with diverse substitution patterns from cyclohexanones or cyclohexenones.Moreover,diverse substituted 1,2-,1,3-,and 1,4-benzenediols were obtained from cyclohexanediones,providing a general and straightforward method for the synthesis of phenols from simple starting materials under mild conditions.
基金financial support from the National Natural Science Foundation of China(22125202,92461312,U24A20487,92361201)Natural Science Foundation of Jiangsu Province(BK20220033).
文摘Cyclohexanone oxime serves as a crucial intermediate in the synthesis of caprolactam,which is an essential precursor for manufacturing nylonfibers,high-performance engineering plastics,and specialized plasticfilms.Catalytic hydrogenation of nitrocyclohexane to cyclohexanone oxime has been documented to be an atom-economical,green and environmentally friendly process.In this review,wefirst introduce the current design rules of catalysts for catalytic hydrogenation of nitrocyclohexane in terms of both active metals and supports.Secondly,we discuss the influence of solvent effects on the cyclohexanone oxime from the nitrocyclohexane conversion.In addition,we concisely discuss typically proposed reaction pathways for the hydrogenation of nitrocyclohexane to produce cyclohexanone oxime.Finally,we provide our perspectives on some issues for catalytic conversion of nitrocyclohexane to cyclohexanone oxime in the future.
基金financially supported by the National Natural Science Foundation of China(22205205,22472151)the Zhejiang Provincial Natural Science Foundation of China(LQ22B030008)the Science Foundation of Zhejiang Sci-Tech University(ZSTU)under Grant No.21062337-Y.
文摘Constructing electrocatalytic overall reaction technology to couple the electrosynthesis of adipic acid with energy-saving hydrogen production is of significant for sustainable energy systems.However,the development of highly-active bifunctional electrocatalysts remains a challenge.Herein,3D hierarchical nickel-copper alloying arrays with dendritic morphology are manufactured by a simple electrodeposition process,standing for the excellent bifunctional electrocatalyst towards the co-production of adipic acid and H_(2)from cyclohexanone and water.The membrane-free flow electrolyzer of Cu_(0.81)Ni_(0.19)/NF shows the superior electrooxidation performance of ketone-alcohol(KA)oil with high faradaic efficiencies of over 90%for adipic acid and H_(2),robust stability over 200 h as well as a high yield of 0.6 mmol h^(-1) for adipic acid at 100 mA cm^(-2).In-situ spectroscopy indicates the Cu_(0.81)Ni_(0.19)alloy contributes to forming more active NiOOH species to involve in the conversion of cyclohexanone to adipic acid,while the proposed reaction pathway undergoes the 2-hydroxycyclohexanone and 2,7-oxepanedione intermediates.Moreover,the theoretical calculations confirm that the optimal electronic interaction,boosted reaction kinetics as well as improved adsorption free energy of reaction intermediates,synergistically endows Cu_(0.81)Ni_(0.19)alloy with superior bifunctional performance.
文摘The liquid phase Beckmann rearrangement of cyclohexanone oxime (CHO) using fuming sulfuric acid as a catalyst is a traditional method for preparing ε-caprolactam (CPL). This process has drawbacks, such as environmental pollution, corrosion of equipment, and low added value of by-product ammonium sulfate. This article designed and prepared a green silica gel-supported trifluoromethanesulfonic acid catalyst for the liquid-phase Beckmann rearrangement of CHO to prepare (CPL). The influencing factors of catalyst preparation and the optimal reaction conditions for Beckmann rearrangement were investigated. It was found that the optimal conditions for catalyst preparation were as follows: raw material silica gel:trifluoromethanesulfonic acid = 1:0.2 (mass ratio), room temperature, stirring time of 2.5 hours, and solvent of acetonitrile, silica gel mesh size is 100 - 200. The optimal reaction conditions for Beckmann rearrangement are CHO: catalyst = 1:2 (mass ratio), temperature of 130˚C, solvent of benzonitrile, volume of 30 mL/g CHO, and reaction time of 4 hours. Under the above conditions, the conversion of CHO is 90%, and the selectivity of CPL is 90%.
基金supported by the National Natural Science Foundation of China(21403070 and 21373088)Innovation Program of Shanghai Municipal Education Commission(13zz038)+2 种基金Key Project of the Shanghai Committee of Science and Technology(12JC1403600)National Key Technology R&D Program(2012BAE05B02)Shanghai Leading Academic Discipline Project(B409)~~
文摘Small-crystal TS-1 was synthesized via a seed-induced approach using ammonia as the alkali source and tetrapropylammonium bromide as an auxiliary structure-directing agent. The TS-1 samples were characterized using X-ray diffraction, N2 adsorption-desorption, Fourier-transform infrared spectroscopy, inductively coupled plasma atomic emission spectroscopy, scanning electron microscopy, and ultraviolet-visible spectroscopy. The use of the colloidal seed reduced the crystal size, and an appropriate amount of silicalite-1 seed assisted Ti incorporation into the TS-1 framework. This method reduces the cost of TS- 1 synthesis because a significantly smaller amount of tetrapropylammonium hydroxide is used. The catalytic performance of the synthesized small-crystal TS-1 samples in cyclohexanone ammoximation was better than that of bulk TS-1 as a result of improved diffusion and a larger number of active tetrahedral Ti centers.
文摘A natural polymer catalyst, silica-supported chitosan palladium complex (abbr. as SiO2-CS-Pd) was found to catalyze the hydrogenation of phenol and cresols to corresponding cyclohexanones in high yield and 100% selectivity at 70 degrees C and 1.01325 x 10(5) Pa mild conditions. N/Pd molar ratio in the complex, temperature and solvents have much influence on the reaction. The reactivity order of reactants was found to be: phenol >m->p->o- The catalyst is stable during the reaction and could be repeatedly used for several times without much decrease in its catalytic activity.
基金supported by the National Natural Science Foundation of China(21473155,21273198,21073159)the Natural Science Foundation of Zhejiang Province(LZ12B03001)~~
文摘A series of Pd catalysts were prepared on different supports（Fe2O3,SiO2,ZnO,MgO,Al2O3,carbon,and Amberlyst-45） and used in the selective hydrogenation of phenol to cyclohexanone in water.The Amberlyst-45 supported Pd catalyst（Pd/A-45） was highly active and selective under mild conditions（40-100 ℃,0.2-1 MPa）,giving a selectivity of cyclohexanone higher than 89%even at complete conversion of phenol.Experiments with different Pd loadings（or different particle sizes） confirmed that the formation of cyclohexanone was a structure sensitive reaction,and Pd particles of12-14 nm on Amberlyst-45 gave better selectivity and stability.
基金VIT University for providing us with research funding and laboratory facilitiesMaratha Mandal Dental College,Belgaum for biological screening support
文摘A series of indazol-2-yl（pyridin-4-yl）methanones, 4 were acquired from 2,6-bisbenzylidene cyclohex- anones, 3 and anti-tubercular drug （isoniazid）, and their anti-tubercular impacts were screened. Among the test compounds used against Mycobacterium tuberculosis H37 Ra cell line in the microplate alamar blue assay, the compounds 4g-j revealed moderate anti-tubercular activity with MIC 12.5 μg/mL, comparable to standard drugs （streptomycin, MIC, 6.25 μg/mL, pyrazinamide, isoniazid and ciprofloxacin with MICs of 3.125 μg/mL）.
基金supported by the National Natural Science Foundation of China(No.20471044)the Natu-ral Science Foundation of Hubei Province Education Comminee(Nos.2004D007 and 2002A00008).
文摘A new environmental friendly catalyst,H_(4)SiW_(12)O_(40)/PAn was prepared andidentified by means of FT-IR,XRD and TG/DTA.Cyclohexanone 1,2-propanediol ketal was synthesizedfrom cyclohexanone and 1,2-propanediol in the presence of H_(4)SiW_(12)O_(40)/PAn The factorsinfluencing tlie synthesis were discussed and the best conditions were found out.The optimumconditions are:molar ratio of cyclohexanone to 1,2-propanediol is 1:1.4,the quantity of catalystis equal to 1.0 percent of feed stocks,and the reaction time is 40 min.H_(4)SiW_(12)O_(40)/PAn is anexcellent catalyst for synthesizing cyclohexanone 1,2-propanediol ketal and its yield can reachover 96.5 percent.
基金Supported by the National Natural Science Foundation of China and Sinopec (20736009)
文摘An innovative green process of producing ε-caprolactam was proposed by integrating ammoximation and Beckmann rearrangement effectively. As a first part of the new process, TS-1 molecular sieve-catalyzed synthesis of cyclohexanone oxime from cyclohexanone, ammonia and hydrogen peroxide was carried out in a batch plant. Cyclohexane was used as the solvent in the three-phase reaction system. The influences of essential process parameters on ammoximation were investigated. Under the reaction conditions as catalyst content of 2.5% (by mass); H 2 O 2 /yclohexanone molar ratio of 1.10; NH 3 /cyclohexanone molar ratio of 2.20; reaction temperature of 343 K; reaction time of 5 h, high conversion of cyclohexanone and selectivity to oxime (both>99%) were obtained. Thus, the three-phase ammoximation process showed equal catalytic activity as TS-1 but much more convenient and simpler for the separation of catalyst in comparison to the industrial two-phase system with t-butanol used as solvent.
基金supported by the National Natural Science Foundation of China (21622308)Key Program Supported by the Natural Science Foundation of Zhejiang Province, China (LZ18B060002)the Fundamental Research Funds for the Central Universities (2017XZZX002-16)~~
文摘The selective hydrogenation of phenol to cyclohexanone is an important process in the chemical industry.However,achieving high selectivity at high conversion rates is highly challenging,particularly under continuous reaction conditions.Here,we found that the presence of Na alkaline additives(NaX,X=CO3^2–,HCO^3–,or OH^–)on Pd/Al2O3 not only promoted the phenol conversion from 8.3%to>99%but also increased the cyclohexanone selectivity from 89%to>97%during the continuous hydrogenation of phenol on a fixed bed reactor.After 1200 h of continuous reaction,no activity or selectivity attenuation was observed and the turnover number was approximately 2.9×10^5.Density functional theory calculations,spectroscopic,and dynamics studies demonstrated that the addition of NaX greatly promoted phenol adsorption and hydrogen activation,thereby improving catalytic activity.Simultaneously,the formation of a“-C=O-Na-”intermediate inhibited the excessive hydrogenation and intermolecular coupling of cyclohexanone,leading to high selectivity.
文摘In the absence of catalyst,70%hydrogen peroxide was used to oxidize succinic anhydride to solid monoperoxysuccinic acid(PSA).Then PSA was applied to synthesis ofε-caprolactone(ε-CL)by oxidation of cyclohexanone in the heterogeneous system.In order to achieve material recycle,solid precipitated in the process of synthesizingε-CL was dehydrated via reactive distillation followed by recrystallization to prepare succinic anhydride,which was characterized by IR(infrared spectra)and1HNMR(1H nuclear magnetic resonance).Effects of molar ratio of PSA to cyclohexanone,acetic acid dosage,reaction temperature,reaction time on conversion of cyclohexanone,yield and selectivity ofε-CL were investigated respectively.The results indicated that conversion of cyclohexanone,yield and selectivity ofε-CL were upto 98.1%,97.5%and 99.4%respectively under the optimal conditions.In addition,in the process of synthesizing succinic anhydride,the optimal yield of succinic anhydride reached 67.4%.
文摘An intrinsic kinetics of cyclohexanone ammoximation in the liquid phase over titanium silicate molecular sieves is investigated in an isothermal slurry reactor at different initial reactant concentrations, catalyst loading, and reaction temperature. The rate equations are developed by analyzing data of kinetic measurements. More than 10 side reactions were found. H2O2 decomposition reaction must be considered and other side reactions can be neglected in the kinetic modeling. The predicted values of reaction rates based on the kinetic models are almost consistent with experimental ones. The models have guidance to the selection of reactor types and they are useful to the design and operation of reactor used.
基金the financial support of the State Basic Research Project ‘‘973’’ by the Ministry of Science and Technology of People’s Republic of China (2006CB202508)
文摘Hollow titanium silicalite （HTS） molecular sieve has been synthesized, and information on its structure, physico- chemical characterization, as well as surface property was investigated by a host of analytical methods, such as XRF, XRD, low-temperature N2 adsorption/desorption, TEM, FT-IR, UV-Vis, 29Si MAS NIVIR, and XPS techniques. The characterization results suggest that HTS zeolite has a special hollow crystal structure and its mesopore volume is larger than that of TS-1 zeolite. The titanium species in this zeolite are composed of the framework tetrahedral Ti （IV） ions and extra-framework octahedral Ti （IV） ions, which tend to disperse into its bulk phase. This zeolite material also has been applied to catalyze the cyclohexanone oxidation process, and the products are not completely consistent with those results obtained by using TS-1 zeolite, which might be caused by their difference in pore structure and pore volume, especially the mesopore volume. Cy- clohexanone oxidation catalyzed by HTS zeolite is a representative consecutive reaction, the main target products of which are e-caprolactone, 6-hydroxyhexanoic acid and adipic acid. The effect of H202/cyclohexanone mole ratio on the cyclohexa- none conversion, the total target product selectivity, the distribution of three target products selectivity and their variations along with reaction time is also researched and analyzed, which indicate that HTS zeolite shows a high performance for the Baeyer-Villiger reaction of cyclohexanone and catalytic oxidation of 6-hydroxyhexanoic acid under mild conditions, and the quantity of active surface titanium species as well as the pore structure and mesopore volume controlling the mass diffusion rate are the key factors determining the catalytic activity of HTS zeolite and product selectivity.
基金financial supports from the National Key R&D Program(2016YFB0301503)the National Natural Science Foundation of China(21776127,21921006)+2 种基金the Jiangsu Province Key R&D Program(BE2018009-2)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the State Key Laboratory of Materials-Oriented Chemical Engineering(ZK201902)。
文摘Selective phenol hydrogenation is a green approach to produce cyclohexanone.It still remains a big challenge to prepare efficient supports of the catalysts for the phenol hydrogenation via a simple and cost-effective approach.Herein,a facile approach was developed,i.e.,direct calcination of activated carbon(AC)under argon at high temperature,to improve its structure and surface properties.The modified AC materials were supported with Pd nanoparticles(NPs)to fabricate the Pd/C catalysts.The as-prepared Pd/C600 catalyst exhibits superior catalytic performance in the phenol hydrogenation,and its turnover frequency(TOF)value is 199.2 h^-1,1.31 times to that of Pd/C-raw.The Pd/C600 catalyst presents both better hydrophobicity and more structural defects,contributing to the improved dispersibility in the reaction solution(phenol-cyclohexane),the better Pd dispersion and the smaller Pd size,which result in the enhancement of the catalytic performance.Furthermore,the as-prepared Pd/C600 catalyst shows a good recyclability.
基金Supported by the National Natural Science Foundation of China(No.21276183)
文摘Mesoporous titanium silicalite-1(TS-1)was hydrothermally synthesized with the addition of triethanolamine(TEA)in the conventional process, and used in the cyclohexanone ammoximation in a continuous slurry reactor. The as-prepared TS-1 was characterized with X-ray diffraction(XRD), scanning electron microcopy(SEM), N_2 adsorption-desorption, Fourier transform infrared(FT-IR)spectroscopy, UV-Visible(UV-Vis)diffuse reflectance spectra and UV Raman spectroscopy. The results indicated that the addition of TEA resulted in the formation of mesopores and the slight increase of framework titanium in TS-1. TS-1 synthesized with the addition of TEA exhibited a higher stability in the cyclohexanone ammoximation than that without the addition of TEA, attributing to the increase of mesopore volumes and the slight increase of the framework titanium in TS-1. However, when the addition of TEA was up to TEA/SiO_2 ratio of 0.24, the crystallinity and framework titanium of TS-1 decreased markedly, and the average crystal sizes of TS-1 increased, with the catalyst stability becoming poor.
基金financially supported by the National Basic Research Program of China (973 Program, 2006CB202508)the Research Program of China Petrochemical Corporation (SINOPEC Group 20673054)the National Key Research and Development Program of China (2017YFB0306800)
文摘Two clean liquid–phase cyclohexanone oxidation routes catalyzed by DHBEA and HTS zeolites, in the absence of organic solvents, have been developed for producing high value-added chemical intermediates. Under optimized conditions,the cyclohexanone conversion reaches up to 60%, and the selectivity of total target products(ε-caprolactone, 6-hydroxyhexanoic acid and adipic acid) is over 90% achieved by the HTS zeolite; while both cyclohexanone conversion and the 6-hydroxyhexanoic acid selectivity are over 95% obtained on the DHBEA zeolite. Both the Lewis and Br鰊sted acid sites of DHBEA zeolite can preferentially activate the carbonyl group of cyclohexanone without any impact on H_2O_2 molecules.Meanwhile, the HTS zeolite can predominantly make H_2O_2 more reactive, which agrees well with the molecular calculation results. Hence, two different Baeyer-Villiger oxidation mechanisms based on the activation of H_2O_2 and cyclohexanone are proposed. Then, 6-hydroxyhexanoic acid is formed via the ring-opening of ε-caprolactone. However, C-OH groups cannot be reactivated by DHBEA zeolite, leading to insignificant adipic acid formation, while the selectivity of adipic acid is 28.5% obtained on the HTS zeolite. Consequently, the higher catalytic performance of the DHBEA zeolite is ascribed to its larger amount of active sites and greater diffusion features than those of HTS zeolite.
文摘A new kind of inorganic polymer, viz, silica-supported polytitazane (Ti-N), and its platinum complex (Ti-N-Pt) were prepared. Cyclohexanone can be obtained in a maximum yield of about 62.2% in the hydrogenation of phenol over Ti-N-Pt at room temperature under atmospheric pressure. The effects of mole ratio of N/Pt in the complex, concentration of the catalyst and reaction temperature on the catalytic activity and selectivity have been studied. The complex can be reused several times without loss in its catalytic activity.
